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INLAK
18th Jul 2001, 22:35
Can any 146 drivers let me know what thier usual flap settings for T/O are. We use Flap 24 for standard runways and Flap 30 in LCY. It appears that other operators use othe settings. How do you find a standard Flap 18 T/O compared to 24, especially on initial climb performance?

fly4fud
19th Jul 2001, 01:22
Hi INLAK !
I'm on the "newer" :D :D RJ stuff, but this is what we basically have.
Usual flap setting is 18. This, most of the times, gives us (?) a better coverage of the 2nd segment which is mostly limiting. In some place, such as the infamous ZRH northely SIDs, you have to use 18 for noise abattement. Strange enough, we are some times better using flaps 24 and sometimes better with 18 using the same runway and conditions, but don't ask me, I sure didn't write that perfbook (called ODM in our company). Seems it should be based on the BAe WOT tables, but is sure doesn't make sense, at least not all the time :)
Nevertheless, another rule, if not overriden by another one (see everybody, this is why aviation as whole is sooo complicated.... :) ) is that when heavier than 37T, flap setting is 24. Now, slippery rwys, ice etc, will have to be dealt with fl30.
As for LCY/LUG/SIR and similar places, we can use up to 33.

Initial climb perf? Yeah, well, like in LCY with 33 it is just a matter to be jumped airborne and then retract the dangling stuff. Fl24 gives you better initial obstacle clearance, but once more penalizes you later.

All this of course based on my modest experience of this pleasant little bird :cool:

notac
19th Jul 2001, 01:56
In general the higher the flap setting the quicker you get off the rwy but the worse your climb performance.

Hence flap 18 will give the highest t/o speed but the best climb performance whereas flap 30 will get you off the rwy quicker but will impare your climb schedule. So short field t/o will require a higher flap setting.

We have no performance for a flap 33 t/o hence we can't use it. However we are shortly going to be approved for flapless take offs (on ferry flights only) :eek:

As for Co SOP's we are free to use whatever setting we see appropriate, except for the obvious senarios

Noise sensitive t/o = flap 18

Contaminated rwy = flap 30.

As for LCY we usually use flap 24 however if your heavy then flap 30. Although with a 100 series flap 18 works very nicely.

[ 18 July 2001: Message edited by: notac ]

IBTheseus
19th Jul 2001, 04:48
Why ever would you want to take off with Flap 0? What is your tire speed limit? It would create a very high demanding V1 abort. We operate with low speed tires. Often F18 is restricted due tire speed limits. :confused:

INLAK
19th Jul 2001, 20:56
Surprised at the F18 on the -100 series! What about landing flaps? Does the RJ still have the problem of the balloon on putting out the first stage of flaps?

fly4fud
19th Jul 2001, 23:17
Ballooning when going fl18? Sure it does. And so it does fl18 to 24. I guess after a few hundred hours you don't feel it that much anymore, unless you're on a raw data (approach ;) ).
IBTheseus , what kind of speed tire are you talking about? Ours (RJ) is 210MPH on the mains and 190 on the nose if memory serves me right. Even when taking off ZRH (noise abate) at 46T in the RJ100, our Vr is at 141kts (162 MPH) and V2 147 kts (169 MPH).

IBTheseus
20th Jul 2001, 11:18
Low pressure tire max 139 kias.
Still fail to see the wisdom in pushing for Flap 0 take offs. :confused:

INLAK
20th Jul 2001, 14:57
I was flying one of ours a few weeks ago, took out F18, autopilot still in, and it gained 300ft!!
We are also limited to a MTOW of 41750kgs due to "economical reasons", which can cause problems on longer flights, though it does help with the perf!

notac
20th Jul 2001, 17:34
Why have a procedure for a flapless take off? The only reason would be if the a/c had a flap problem away from base with no engineering cover. It would be a way of recovering the a/c without having to pay for third party engineering.

As I said this procedure will only be allowed on a ferry flight and with specific written permission from the boss.

Capt Claret
20th Jul 2001, 21:35
We use F24 as the preferred T/O flap setting as compromise between F18 TODR & Tyre speed V F30 2nd segment. However it is only preferred, not mandated.